The present invention relates to a novel, improved radiator construction and in particular, a radiator construction utilizing a unique tube construction which allows for the use of a simple, less expensive seal construction to provide improved tube retention in the radiator.
In heavy duty radiators, particularly radiators used in heavy, earth moving equipment, the core of the radiator is constructed from a series of cooling conduits or heat exchanger tubes attached to and in communication with upper and lower radiator tanks. These tanks receive cooling fluid such as water, with or without antifreeze, as it passes to and from the engine as circulated by a water pump. Cooling fins are typically attached to the cooling conduits to facilitate heat transfer.
It is undesirable to permanently attach or affix the conduits to the radiator tanks because if any one of the heat exchange conduits in the core develop a leak, the entire core must be removed and repaired. This is a particularly vexatious problem in heavy duty earth moving equipment wherein the continued jarring of the equipment and the vibration induced by the engine has a tendency to compromise the connection between the tanks and the heat exchange conduits with the resultant tube movement causing leaks in some applications.
A solution to this problem is illustrated in U.S. Pat. No. 3,391,732 the teachings of which are incorporated by reference herein. U.S. Pat. No. 3,391,732 describes a radiator core constructed from a series of conduits, each of which has either end removably mounted in the framework, or headers, of the radiator which provide a portion of the upper and lower radiator tanks or reservoirs. As illustrated in U.S. Pat. No. 3,391,732, the bottom of each conduit of the radiator core is placed in an elastomeric seal having a shoulder around the outer periphery of the seal. This shoulder, in turn, engages the header plate when the seal is placed in the openings of the header. Positioned in the interior portion of the seal is a radially positioned groove or recess that mates or cooperates with a radially outward extending flange or collar contained in the heat exchange conduit. This seal construction is illustrated in FIGS. 4 and 5 of U.S. Pat. No. 3,391,732. The interrelationship of that seal with the flange of the cooling conduits is illustrated in FIG. 3 of U.S. Pat. No. 3,391,732. This prior art construction is also reproduced in FIGS. 3 and 4 of this application. Referring to FIGS. 3 and 4, the prior art construction includes a header 2 having a circular opening 3 therein. An elastomeric seal 18 is positioned within opening 3 of header 2. The upper portion of seal 18 is formed to provide an elastomeric seal shoulder 14 having a diameter greater than opening 3 so as to prevent the seal from passing downwardly through the opening 3 in header 2. The center portion 16 of seal 18 receives a heat exchange tube having a cylindrical conduit end 8. Cylindrical end 8 of heat exchange tube 1 is maintained in position within seal 18 through the interaction of groove or recess 22 contained in seal 18 and flange or collar 20 extending outwardly from the surface of conduit end 8. Positioned above the cylindrical portion of conduit 8 is a flattened conduit section 4 having affixed thereto heat exchanger fins 6.
The structure described in U.S. Pat. No. 3,391,732 and as illustrated in FIGS. 3 and 4 of this application has, over the years, proven to be a reliable method of providing a removable tube radiator core structure. If one heat exchange tube fails, that tube can be replaced instead of replacing the entire radiator. The elastomeric nature of the seal in combination with the interaction of the collar 20 on the tube and the interior recess or groove 22 in the seal absorb shock and vibration forces and thermal expansion and contraction to maintain the tube in a sealed positioned.
As the art progressed, the materials used in the design of the seals illustrated in U.S. Pat. No. 3,391,732 changed and evolved so as to provide a longer life in the extremes of temperature and chemicals to which such elastomeric seals were exposed in the field. New elastomeric materials were developed which are more resistant to the environment encountered in heavy earth moving equipment but which are also much more expensive. When seals made from these new elastomeric materials were introduced, it was discovered that these materials were more vulnerable to molding problems and seal 18 with its recess 22 were much more difficult to mold. Specifically, to provide a reliable retention of the tube, it is necessary that there be close interaction between the recess or groove in the seal and the flange or collar in the heat exchange conduit engaging that recess. In particular, because of the nature of the current elastomeric materials used to produce seals for the structure shown in U.S. Pat. No. 3,391,732, it became more difficult to insure that the structure was molded with consistent integrity to the intended design dimensions so as to prevent any inadvertent tube movement and subsequent leakage. While it is certainly possible to prepare elastomeric seals as described in U.S. Pat. No. 3,391,732, through existing molding techniques, utilizing fluid and temperature resistant, state-of-the-art polymers, the cost, due to the size of the seal and the rejection rates associated with the production of such seals, has increased and has increased significantly the cost of manufacturing a reliable radiator core construction.
Other prior art structures are illustrated in FIGS. 1 and 2 and FIGS. 5 and 6 accompanying this application. The prior art structure illustrated in FIGS. 1 and 2 utilize an elastomeric seal 12 placed within opening 3 in header 2. An elastomeric seal shoulder 14 prevents the seal from passing through opening 3. Positioned within the central portion 16 of the seal is the cylindrical conduit end 8 of heat exchange tube 1 which in turn is integrally formed with and attached to flattened conduit 4 having attached thereto heat exchange fins 6. A washer 10 is attached to the cylindrical portion 8 of the conduit and interacts with seal shoulder 14 to prevent the heat exchange tube 1 from passing downward into opening 16 of the seal and/or opening 3 in header 2. The structure illustrated in prior art FIGS. 1 and 2 absorbs, in part, vibration forces, and downward impact forces in vertical tube application but there is nothing contained in that structure to prevent the seal 12 or the heat exchange tube 1 from being displaced upward and out of the seal or sideways out of the seal in horizontal applications. As a result, a safe, reliable seal is not consistently achieved.
Another prior art structure is illustrated in FIGS. 5 and 6 of this application. As illustrated in these Figures, an elastomeric seal 24 is positioned within opening 3 in header 2 and adapted to receive the cylindrical portion 8 of heat exchange conduit 1. Seal 24 has an outwardly extending shoulder 14 extending beyond opening 3 so as to prevent the seal from passing downwardly through opening 3 in header 2. Inwardly extending projections 26 extend inward towards the center portion 16 of seal 24 and are adapted to engage the bottom of cylindrical end 8 of tube 1 so as to control it from passing further downward through the center portion 16 of seal 24. As in case of the structure illustrated in FIGS. 1 and 2, this structure does not retain the cooling conduit 1 in position in a manner designed to prohibit the conduit from rising upwardly out of opening 16 or to otherwise move within that opening. This movement can result in leakage. In addition, the projections 24 do not provide reliable mechanism for preventing the conduit 8 from moving within the center section 16 of seal 24. This movement can also lead to undesired, unexpected leaks. Further, these seals, because of their size, require more material to construct them and because of the projections, are somewhat complex to make. Finally, this structure is more vulnerable to dimensional changes.